Circuit controlling device



Oct. 31, 1939. J. SANDBN .1 .083

CIRCUIT CONTROLLING DEVICE Filed Jan. 50, 1937 2 Sheets-Sheet 1 Irma/0192122 WITNESSES. n a INVENTOR ZQ/WZT 15 fj9 z rorzze 5422647. q BY WM 7 Z; X! 6' ATToPmEv Oct. 31, 1939, J. SANDIN CIRCUIT CONTROLLING DEVICE Filed Jan. 50, 1937 2 Sheets-Sheet 2 INVENTOR [f X/ ATTORNE Patented on. 31', 1939 PATENT OFFICE 2,178,083 CIRCUIT CONTROLLING DEVICE Jerome Sandin, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania'.

Application January 30, 1937, Serial No. 123,236

18 Claims.

My invention relates to circuit controlling devices in general and more particularly to trip devices for circuit breakers.

In certain applications of circuit breakers principally in installations aboard war craft such as battleships and the like, the circuit breakers are often subjected to severe shocks and heavy vibrations of sufficient magnitude to move the sensitive trip elements of the breaker to cause tripping of the breakers resulting in interruptions of the electric circuits. The interruptions are likely to occur when continuity of service is most needed, as for example during the heat of battle, or upon an impact or collision.

Many efiorts have been made to design circuit breaker structures which would be insensitive to shock. Few, if any, of the breakers thus developed'have proved entirely satisfactory principally because in making the structure shock proof, other desirable features had to be sacrificed. It is accordingly an object of my invention to .providean improved shock proof circuit breaker having a trip device that is simpler. more efficient and reliable in operation, and less expensive to manufacture and service, than trip devices heretofore known or used.

Another object of my invention is to provide a trip device embodying an improved trip bar structure and manner of mounting the same.

Another object of my invention is to provide a trip device embodying an improved electromagnetic trip element structure and manner of mounting the same.

Another object oi my invention is to provide a shock proof trip device embodying an improved trip bar structure and a cooperating improved electromagnetic trip element structure both of which will be substantially unaiiected by shocks or vibrations.

The features that I consider characteristic of my invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will Fig. 3 is an elevational view of the improved trip device.

Fig. 4 is a sectional view of the trip device taken on the line IVIV of Fig. 3.

Fig. 5 is a sectional view of the trip device taken on the line VV of Fig. 3.

The invention has been shown in connection with a particular form of multi-pole circuit breaker for illustrative purposes only. It will be understood, however, fromthe following description that the invention is capable of more or less general application to various other forms of circuit controlling devices and electrical devices.

Since the invention is particularly concerned with the electro-responsive trip device and since the circuit breaker wherein my invention has been embodied is completely described in the copending application of Harry J. Lingal, Serial No. 637,749, filed October 14, 1932, and assigned to the assignee of this invention, the description will be limited to setting forth the various elements. Application Serial No. 637,749 became Patent No. 2,083,305 on June 8, 193?.

Referring to the drawings, the base i is oi molded insulating material and has mounted thereon terminals 3 and 5, the removable unitary trip device l, the circuit breaker operating mechanism 9 which has associated therewith the assemblage of the switch members it, the are extinguishers l3, and the stationary contact assemblages iii of the switch members. The assemblage of the switch members i l andthe stationary contact assemblage l5 combine to form a plurality of poles. Each of the poles is insulated from the adjacent pole by means of insulating barriers l?! (Figs. 1 and 2) which are molded into the base 11, These insulating barriers ii are adapted to align with similar shaped barriers 2i molded in the cover it] which is likewise of insulating material. The operating member 23 has a removable handle 25 and is pivoted to the main frame it of the operating mecha main moving contact I8 and the flexible shunt- 39 which is associated with each of the switch members, the terminals 35 of the trip structure 1, and finally through thetrip structure to the other terminal 5.

, The assemblage of the switch members II is pivoted to the main frame H of the operating mechanism 9 by means of a pin 42. A steel tie bar 43 serves to rigidly mechanically interconnect the three switch members II, there being only one pivot point. Each of the switch members I I includes a clamp member 45 for engaging the tie bar 43. The clamp members are secured to the tie bar by means of bolts 41 .or any other suitable form of securing means. A square tube 48 of insulating material is disposed between the tie bar 43 and the clamping members 45 to insulate the several poles of the breaker fromeach other. The main moving contacts I8 are pivoted to the clamp members 45 through the agency of pivot pins 49. A projecting auxiliary (contact member 5| is provided for engaging the stationary arcing contact 53. Springs are provided in biasing each of the main moving contact members I9 toward the cooperating main stationary contact member I5 with a predetermined normal fprce.

The end of each of the shunts 39 adjacent the switch members II is secured to the pivotally mounted contact members I 8 through the agency of rivets 51. Each of the main moving contact members I8 has a rearwardly extending portion 59 for engaging the end of the shunt 39 and for defining the limit of movement of eachof the contact members I8 under the biasing action of the contactsprings 55. The shunts 39 for the two outer poles are rigidly afiixed' to the base I by means of screw fastenings GI and 64 which pass through suitable openings in the shunts. The shunt 39 for the central pole is held in place by four screws 82 which engage threaded openings in the base of the main frame 4|. The shunts 39 are of laminated construction being built up of a plurality of thin sheets of copper. The clamp member 45 of the central switch member has openings 88 for engaging the contact assemblage pivot pin 42, openings 81 for engaging thebreaker operating mechanism, and slotted openings 69' for clearing the pivot pin 15 of the main operating member 23.,

- Any suitable type of arc extinguishing means may be used. The form illustrated is similar to that shown in Patent-No. 13963164 of M. W. Brainard, issued February '1, 1933, and assigned to the assignee of this invention.

The operating mechanism 9 comprises in general a base or main frame 4|, a pair of toggle links 11 and 19, one end of which is connected to the assemblage of switch members II through the central clamp member 45, a carrier lever 8| for releasably restraining the other end of the toggle links 11 and 19 in operative position, an operating member 23, an overcenter spring unit 83 for connecting the operating member 23 to the knee of the toggle links, and the operating handle 25.

The base 4| is positioned above the conducting shuntf39 of the central pole and is rigidly afiixed to the base by means oi. the screw 82. One end of the toggle link 11 operatively engages the openings 51 in the central clamping member 45 through the agency of a pivot pin 89. The other end of the toggle link 11 is pivoted to one end of.the toggle link 19 by means of'a knee pivotpin 9|, the toggle links 11 and "are provided with portions which engage when the breaker is in the closed position to define the Emit of upward movement of the knee of the toggle.

The overcenter spring unit 83 operatively'connects the end 95 of the operating member ,23 with the knee pivot pin 9| of the toggle links and exerts a tension force therebetween. The

overcenter spring unit 83 comprises a frame 95 .one end of which is adapted to engage the knee pivot pin 9| and the other end of which has a circular opening to accommodate the plunger member 91. The overcenter spring 98 which is itself in compression is positioned between the end of the 'frame 98 and the enlarged portion 89 of the plunger 91. The other end of the plunger 91 pivotally engages the end 95 of the operating member 23 by means of a pin I8| which fits in a suitable recess I82.

- The/end I83 01 the toggle link 19 is provided with a circular bearing portion I84 which engages a suitable recess in the end'oi the bell crank carrier lever 8|. Two retaining plates I85 are disposed on the outer sides of the carrier 8| to prevent the bearing portion I84 irom'mov-.

ing side ys and disengaging the recess.

The bel crank carrier lever 8| has a projecting portion I81 for engaging the latching lever III and is pivoted to the base H at its apex by means of a pivot pin I89. The portion I81 of the carrier 8| extends along the base 4| to form what might be termed a tail portion. The perpendicular distance from the center of the carrier pivot pin- I89 to the line of action of the toggle lever 19 is considerably less than the distance from the center point of the carrier pivot pin I89 to the end of the projecting portion I81 of the carrier 9 I. This gives the carrier lever 8| an appreciable mechanical advantage over the toggle.

The overcenter spring unit 83 at all times exerts a force on the carrier lever 8| biasing the lever in a clockwise direction and it is to restrain the carrier lever in the operative position that the latching lever III is provided.

The latching lever III includesa projecting portion II2 for engaging the end of the section I81 of the carrier lever 8|, and a portion 8 for engaging the trip latch I58 (see Fig. 4). One end of the latching lever III is pivoted to the base 4| by the pivot pin II5 adjacent the point of engagement with the tail piece I81 01 the carrier member 8|. The projectin P rtion II2 of the latching lever normally overhangs the end of the portion I81 of the carrier lever 8| and thus holds the carrier in an operative position by preventing it from moving upward. The free" end 'of the, latching lever I II is releasably re strained in the position shown in Fig. 2 by reason .of the engagement of the portionII3 with the trip latch I58, which latter forms a part of the trip device 1.

'The improved trip structure 1 is a unitary device entirely assembled upon its own base I 53 of molded insulating material and is completely removable from the circuit breaker; the screw fastenings 3| and 33 being utilized to mount the trip structure on the base I of the circuit breaker and also to make the necessary electrical connections. The trip device 1 includes a magnetically responsive element for each of the poles of the breaker -.and the mechanism of the device is so arranged that a heavy'magnitude overload in-the circuit controlled by any one of the poles will actuate the of the breaker to interrupt the circuit of each of the poles.

Each oi. the magnetically responsive trip elements of the trip device is mounted on the trip base I53 through the agency of a metallic yoke U55 of non-magnetic material. The yoke I55 is substantially U-shaped and has a pair of outstanding lugs I5'I for pivotally supporting a U- shaped armature I59 of magnetic material. The armature I59 is pivotaily mounted on the lugs I51 by means of pivot pins I6I. Each of the legs of the yoke I55 is provided with an offset angular end portion I63 for supporting a transverse stationary core member I65 of magnetic material."

The stationary core member I65 is secured to' the ofiset ends I63 of the yoke I55 by means of screw iastenings I61. Each of the armatures I59 is adapted to be biased towards its normal position away from its stationary core, as shown in Figs. 4 and 5, by means of a'pair of biasing springs Q69. The springs I69 are disposed upon studs ill which are secured to the base I53 of the trip device. One end of each of the springs I69 engages a slidable bushing I13 which is slidably mounted on the stud HI, and the other end of each spring is held in stressed condition by means of a washer fitted on the stud and a cotter pin passing through the end of the stud. The force exerted by the compression springs I69 causes the slidable bushings H9 to engage and bias the armatures 859 to their normal position. An energ zing conductorv H9 is provided for each of the magnetically responsive trip elements. The ends of each conductor form the terminals 35 and 31 of each of the magnetically responsive trip elements and the body portion passes between the legs of the armature I59 and the yoke I55, and over the stationary core I55. The current flowing in the conductor when the circuit breaker is closed sets up a circular magnetic field about the conductor which produces a magnetic flux in the armature i55i and the core I65. This flux passes through the armature, across the air gaps, and through the stationary core I65 and produces an attracting force between the legs of the armature I59 and the core i (55 which tends to move the armature to attracted position with its legs against the stationary core-I65. Under normal current conditions, the biasing force produced by the springs I69 prevents the armature from being moved from its normal position. Under abnormal current con ditions, such as occur on short circuit or heavy magnitude overloads, the. attracting force produced by the flux becomes suflicient to overcome the biasing action of the springs I69 and move the armature to its attracted position to efi'ect a tripping operation of the breaker, as will be hereinafter described.

The pivot pins I6I of each of the armatures H59 are disposed as close as is possible to the center of mass of the armature, and each armature is provided with a balanced weight means or cross piece 08 I of non-magnetic material in order to stat cally and dynamically balance the armature. v The feature of statically and dynamically balancing the armature is particularly important in that it prevents the armature from being moved toward its attracted position in response to jarring forces or heavy vibrations so that by this arrangement each of the armatures is rendered substantially shock proof. The cross piece or balance member MI is secured transversely across the ends of the iegs of the armature by means of the screws I92.

The length of the air gaps between the armature I59 and the stationary core I65 in the case device.

of each of the electromagnetic tripping means is made suiiiciently large so that any small movement of the armature toward the core, which may be caused by shock,- will be ineffective to increase the attractive pull a suflicient amount to move the armature to attracted position, even in the, case of overload currents which are only slightly below the tripping value.

In order to provide for accurate positioning of the trip device with respect to the path of movement of the latching lever II I, there is provided a metallic bracket I89 (Fig. 5) which is rigidly secured to the center portion ofthe trip base I53 by means of screw fastenings (not shown). The bracket I83 has a portion R85 which is of substantially the same outline as the center terminal 35 of the trip device and is thus adapted to be fastened tothe base i or the circuit breaker by means of the screw fastenings iii of the central pole. The center screw fastenings 35 would probably be sufiicient to accurately position the trip device but in order to insure that the positionis correct, there is provided an additional positioning means which consists of a male member I81 which extends downwardly through a suitable opening in the center terminal 35 and engages in a cooperating female portion 089 provided in the center shunt 39, this shunt being securely fastened to the base i and accurately positioned with respect to the operating mechanism by means of the screw fastenings 62 previously mentioned.

The bracket 683 has ,an opening I9I in the upper portion, the trip lever i5ll being pivotally mounted therein through the agency of a pivot pin I99.

The trip lever M is preferably constructed of metal and has a projecting portion I95 for engaging the latch engaging means associated with the latching lever iii. A spring i9! is provided for biasing the trip lever ll to its latched position and a notch 999 is provided in the trip lever for engaging a bracket carried by the trip bar 20 i The trip bar 28!] is constructed of molded insulating material and extends across all three poles oi the breaker. It is pivotally supported at two points adjacent and on either side of the trip lever 65d by means of a pair of lugs 203 (Fig. 3) which project from the bracket 983 of the trip The lugs 263 are provided with openings for the reception of pivot pins 205 carried by the trip bar 201']. A filler screw 2b? is screwed into a portion of one of the lugs 263 in order to maintain the trip bar in pivotally mounted position. The body of the screw 2M substantiallyfills the space between the pivot pin 295 and the opposite edge of the recess into which projects the pivot pin 205. This particular form of pivotal mounting means for the trip bar permits the trip bar to be easily mounted or dismounted from the lugs 203.

The trip bar 295 engages the trip lever I50 through the agency of an angular bracket 209 (Fig. 5) one end of which engages in the notch 889 of thetrip lever i511 and the other end of which is rigidly secured to the trip bar by a pair or" rivets. A compression spring 2H biases the trip bar clockwise (Fig. 5) about its pivot axis to itslatching position. 'Ihree plates 2I3 are secured in spaced relation on the trip bar by means of rivets 2. Each of the plates 2I3 extends downwardly to a position adjacent its correspending armature I59 and is adapted to be enrence of an overload.

response to jarring forces and heavy vibrations.

Thus the pivoted trip bar as well as each of the pivoted armatures is rendered substantially shock proof.

This position of the pivot points of the trip bar on either side of and adjacent the latch load center spring unit 03 below the center line of the toggle unit 19. The circuit breaker operating mechanism is completely resettable by means associated with the operating member 23.

The operation of the trip device is substantially as follows: Upon the occurrence of an overload in the circuit controlled by any one of the poles of a breaker, the flux setup in the armature I59 and the stationary core I55 of the particular pole of the breaker on which the overload occurs reaches a sumcient magnitude to produce an attracting force between the armature I50 and prevents any flexing or bending of the trip bar I which .would tend to throw the same. out of balance.

The end H3 of the latching lever III is provided witha bifurcated portion in which is pivotally mounted a latch 2I9. The latch 2I9 is pivotally mounted by means of a pivot pin HI and is biased to latching position by means of a spring 223, Clockwise rotation of the latch 2i! under the biasing influence of the spring 223 is limited by the engagement of a tail portion of the latch with the end II3 of the latching lever III.

The latch 2I9 is adapted to be engaged and held by the latch lever I50 to restrain the latching lever III in its normal positionas shown in Figs. 1 and 5.

The exact details of operation of the circuit breaker mechanism 9 are set forth in the previously mentioned application of Harry J. Lingal and the disposition of the various mechanism in the open, closed, and tripped positions are shown in the drawings accompanying that application.

, center spring unit 83.

Generally, however, the operation is as follows. To manually move the contacts from the closed position shown in Fig. 2 to the open position, the handle 25 is moved downwardly. This downward movement causes the toggle links 11 and I9 to collapsetoward the base I under the influence of overcenter spring unit 03. The collapse of the toggle causes the entire assemblage of the switch members I I to pivot about the pin-l2 and move to the open position with a snap action. To close the contacts manually, the operation is substantially reversed: the handle 25 is moved upwardly and the toggle is restored to the position shown in Fig. 2 by the force exerted by the over- The contacts close as well as open with -a snap action due to the progressive acceleration given by the toggle.

When a circuit breaker is in the closed circuit position and an overload of suflicient magnitude to actuate the trip device occurs in the circuit controlled by any one of the poles of the breaker; the latching lever'l50 is released to free the end II! of the'latching lever III by the movement of the trip bar 20I to trip position. The latching lever III is biased counter-clockwise (Fig. 2)

about its pivot pin 5' and as soon as it is released, it moves'so that the portion I I2 thereof disengages the cooperating end portion I01 of the carrier lever ii. The entire mechanism is now free to move under the biasing action of the contact springs 55. These springs cause the assemblage of the switch members to move clockwise about. the pivot pin 42 and at the same time cause the toggle link 11 and I9 to be moved toward the base of the circuit breaker. The combined result of these movements is to cause a clockwise movement of .the carrier lever 8| and a collapse of the toggle links toward the base I due to the bringing of a center line of the overthe core I65; which is sufllcient to move the armature I50 to its attracted position against the biasing action of the springs I05. Movement of the armature from'its normal to its attracted position causes the same to engage and move the 'plate member 2I5 to effect a counter-clockwise rotation of the trip bar 20I.

The counterclockwise rotation of the trip bar 20I causes the bracket 20! carried thereby to release the latch lever I50 thus permitting the latch 2I0 aflixed to the free end II3 of the latching lever III to disengage the projection I05 of the'latch lever I50. The free end of the latching lever III is biased away from-the base by the operating spring means and it, therefore, immediately moves to the tripped position thereby causing the contacts of the breaker toopen. As soon as the latch 2I9 has disengaged the projection I95 on the latch I50, the biasing spring 223 restores the latch 2I9 to latched position, shown in Fig. 5. After the contacts of the breaker have been opened by the tripping operation described above. the armature is returned to its normal position by the biasing springs I00. This permits the trip bar to return to its latching or normal position under the influence of its biasing spring 2 so that the trip device is reset. The return of the trip bar to its normal or latching position causes the bracket 209 to reengage the notch I of the trip lever I50 which has in the meantime been reset to normal position by its spring I01, so that the trip device is thus automatically reset. .Before the breaker can be reclosed it is necessary that the latching lever Ill be returned to its original or latched position. This is accomplished by moving the operating handle 25 of the breaker to the full open circuit position. The breaker may then be manually closed in the manner described previously in connection with the manual operation.

The feature of both statically and dynamically balancing the pivoted trip bar and each of the pivoted armatures renders the trip device and the breaker substantially shock proof. The location of the pivot points of the trip bar on either side of and close to the latch load prevents the trip bar from being bent or flexed and thus thrown out of balance.

By my invention, I have provided an improved shock proof trip device that is simpler, more emcient and reliable in operation and less expensive to manufacture than any trip devices heretofore known or used.

, While I have shown and described the invention in accordance with the provisions of the patent statutes, it is to be understood that various changes in the details of the structure may be made without departing from the spirit of the invention. I desire, therefore, that the invention be limited only by the reasonable construction of the appended claims and by the prior art.

I claim as my invention: 1. In a circuit breaker having a spring biased actuating member releasable to eflect a circuit opening operation, the combination'of a trip device comprising releasable latch means for restraining said actuating member in an inoperative position, a pivoted trip member of nonsymmetrical shape movable from a normal position to tripping position to release said latch means to free said actuating member, electro-responsive means operable in response to predetermined conditions to move said trip member to tripping position said trip member being both statically and dynamically balanced to render the same substantially shock proof.

2. In a multi-pole circuit breaker having a spring biased actuating member releasable to effect opening of the breaker, the combination of a trip device comprising releasable latch means for'restraining said actuating member in an inoperative position, a rotatably mounted trip bar. extending across at least two poles of the breaker movable from a normal position to tripping position to release said latch means to free said actuating member, a plurality of electroresponsive means each operable in response to predetermined conditions to move said trip bar to tripping position, said trip bar having a plurality of projections along its length and a balancing mass opposite each projection for statically and dynamically balancing said trip bar to render the same shock prooi'.

3. In a multi-pole circuit breaker having a spring biased actuating member releasable to efiect opening of the breaker, the combination of a trip device comprising a latch member for restraining said actuating member in an inoperative position, a rotatably mounted trip bar ex tending across at least two poles of the breaker,

said bar being biased to a normal position in. which it holds said latch member in latching position to restrain said actuating member, a plurality of projections on said bar along its length, a plurality of electroresponsive trip elements each operable in response to predeter-' mined conditions to engage one of said projections and move said trip bar to a tripping position to release said latch member and free said actuating member, said trip bar having a balancing mass opposite each projection for statically and dynamically balancing said bar to render the same substantially shock proof.

4. In a multi-pole circuit breaker, a plurality of pairs of relatively movable contacts forming a plurality of poles, a common operating mechanism for opening and for closing said contacts, a spring biased actuating member releasable to efiect opening of said contacts, the combination of a trip device comprising a latch for restraining said actuating member, a rotatably mounted trip bar extending across at least two poles of said breaker biased to a normal position and having an element thereon for engaging and restraining said latch in latching position to hold said actuating member, a plurality of projections. on said bar along'its length, a plurality of electro-' responsive means each operable in response to predetermined conditions to engage one of said projections and move said trip member to tripping position to release said latch and free said actuating member, said trip bar having a balancing'mass oposite said latch engaging element and opposite each projection for statically and dynamically balancing said bar to render the bar substantially shock proof.

-5. In a circuit breaker provided with a spring biased actuating member releasable to effect a circuit opening operation of the breaker, in combination, a trip device comprising releasable latch means for restraining said actuating member in a predetermined position, electro-magnetic means including a pivoted armature of non-symmetrical shape biased to a normal position and movable to an attracted position in response to predetermined'conditions to efi'ect release of said latch means to free said actuating member, said armature being statically and dynamically balanced to prevent the same from being moved by jarring forces.

6. In a circuit breaker relatively movable contacts, operating mechanism for opening and for closing said contacts, a spring biased actuating member releasable to effect opening of said contacts, the combination of a trip device comprising releasable latch means for restraining said actuating member in a predetermined position, a

pivoted U shaped armature biased to a normal position and movable to an attracted position to efiect release of said latch means to free said actuating member, a core member mounted adjacent the legs of said armature and an energizing conductor connected in circuit with said contacts and extending between the legs of said armature, said core and conductor being operable in response to predetermined conditions to move said armature to attracted position, said armature being statically and dynamically balanced to render the same substantially shock proof.

7. In a circuit breaker provided with a spring biased actuating member releasable to effect a.

circuit opening operation, the combination of a trip device comprising releasable latch means for restraining said actuating member in a predetermined position, a pivoted trip member biased to a normal position and movable from said normal position to a tripping position to effect release of said latch means to free said actuating member, electro-magnetic means including a pivoted armature biased to a normal position and movable from said normalposition to an attracted position in response to predetermined conditions to move said trip member to tripping position, said trip member being statically and dynamically balanced and said armature being at least statically balanced to prevent movement of the said elements in response to jarring forces.

8. In a circuit breaker, relatively movable contacts, operating mechanism for opening and for closing said contacts, a spring biased actuating member releasable to effect opening of said contacts, a trip device comprising a latch for restraining said actuating member in a predeterrninedposition, a pivoted trip member biased to a normal position for restraining said latch to hold said actuating member, electromagnetic means including a pivoted armature biased to a normal position and movable from said normal position to an attracted position to move said trip member to a tripping position to release said latch and free said actuafting member in response to predetermined conditions, said trip member comprising a releasable latch for restraining said actuating member, a pivoted trip bar extending across two or more of said poles biased to a normal position to restrain said latch in latching position and movable to a tripping position to release said latch to free said actuating member, said trip bar being pivoted on both sides of and adjacent said latch, a plurality of electro-responsive trip elements one for each pole each operable in response to predetermined overload conditions in the circuit of its pole for moving said trip bar to tripping position, said trip bar being statically and dynamically'balanced to prevent the same from beingmoved in response to jarring forces.

10. In a. multi-pole circuit breaker, a plurality of pmrs of relatively movable contacts forming a plurality of poles, operating mechanism for opening and for closing all of said pairs of contacts, a spring biased actuating member releasable to effect simultaneous opening of all of said pairs of contacts, in'combination, a trip device comprising a releasable latch for restraining said actuating member, a pivoted trip bar extending across two or'more of said poles biased to a normal position to restrain said latch in latching position and movable to a tripping position to release said latch to free said actuating member and a plurality of electro-responsive trip elements, one for each pole each operable in response to predetermined overload conditions in the circuit of its pole for moving said trip bar to tripping position, said trip bar being statically and dynamically balanced to prevent the same from being moved in response to jarring forces.

11. In a--multi-pole circuit breaker having a plurality of pairs of relatively movable contacts forming a-pluralityof poles, a common operating mechanism for simultaneously opening or closing said pairs of contacts, and a spring biased actuating member releasable to effect simultaneous opening of said pairs of contacts, the combination of a trip device comprising a releasable latch means for normally restraining said actuating member, a pivotally mounted trip. bar extending across two or more poles of said breaker biased to a normal position, and movable to a tripping position to eifect release of said latch means to free said actuating member, a plurality of electromagnetic trip means one for each pole each including a pivoted armature biased to a, normal position and movable to an attracted position in response to abnormal conditions in the circuit of its pole to move said trip bar to tripping position, said trip bar being statically and dynamically balanced to prevent the same from being moved by jarring forces or vibrations.

12. In a multi-pole circuit breaker having a plurality of pairs of relatively movable contacts forming a plurality of poles, a common operating mechanism for simultaneously opening or closing said pairs of contacts, and'a spring biased actuating member releasable to effect simultaneous opening of said-pair's of contacts, the combination of a trip device comprising a releasable latch means for normally restraining said actuating,

member, a pivotally mounted trip bar extending across two or more poles of said breaker biased to a normal position, and movable to a tripping position to effect release of said latch means to free said actuating-member, a plurality of electromagnetic trip-means one for each pole each including a pivoted armature biased to a normal position and movable to an attracted position in response to abnormal conditions in the circuit of its pole to move said trip bar to tripping posi-.

. sponse to tion, said trip bar and each of said armatures being statically and dynamically balanced to prevent their being moved to trip the breaker in response to jarring-forces or vibrations.

13. A trip device for a multi- 1e circuit 5 breaker provided with a spring biased actuating member releasable to effect opening of the circuits of all the poles of the breaker, said trip device comprising a releasable latch means for restraining said actuating member, a pivoted trip 10 bar extending across two or more poles of the breaker biased to a normal position for restraining said latch means in latching position and movable to a tripping position to release said latch means and free said actuating member, 15

member releasable to effect opening of the cirg cuits of all the poles of the breaker, said trip device comprising a releasable latch means for restraining said actuating member, a pivoted trip bar extending across two or more poles of the breaker biased to a normal position for restrain- 3o ing said latch means in latching position and movable to a tripping position to release said latch means and free said actuating member,

and a plurality of electro-responsive means, one

for each pole, each operable in response to pre- 35 determined abnormal conditions in the circuit of its pole to move the trip bar to tripping position; said trip barbeing statically and dynamically balanced to prevent its being moved in rejarring forces, and said bar being 4 pivotally supported adjacent said latch means on both sides thereof to prevent distortion of said bar when subjected to latch load and jarring forces to preserve its balance. I

15. A trip device for a circuit breaker pro- 43 vided with a spring biased actuating member releasable to effect a circuit opening operation, said device comprising releasable latch means for restraining said actuating member in a predetermined position, electro-magnetic means including a. U shaped pivot armature biased to a normal position and movable to an attracted position to effect release of said latch means to free said actuating member, a stationary core mounted adjacent said armature, an energizing conductor for said core and armature connected in the circuit controlled by the breaker, said core and conductor being operable in response to predetermined conditions to cause movement of said armature to its attracted position, said arms.- so ture being statically and dynamically balanced to prevent the same from being moved by jarring forces or vibration.

16. A trip device for a multi-pole circuit breaker provided with a spring biased actuating as member releasable to effect opening of the circuits of all of the poles of the breaker, said device comprising a releasable latch means for restraining said actuatingmember, a trip bar pivotally supported close to and on both sides of 111 said latch means and extending across two or; more poles of the breaker, said bar being biased to normal position to restrain said latch means in latching position andmovable to a tripping position to release said latch means to free said actu 7| ating member, a plurality of electromagnetic trip means, one for each pole, each including a pivoted U-shaped armature biased to a normal inoperative position and movable to an attracted position in response to a predetermined overload on the circuit of its pole to move said trip bar to tripping position; said trip bar and each of said armatures being statically and dynamically balanced to prevent their being moved by jarring forces or vibrationsto trip the breaker.

17. In a, multi-pole circuit breaker having a pluralityof pairs of relatively movable contacts and an actuating member releasable to eflect simultaneous opening of said pairs of contacts, the combination of a trip device comprising a pivotally mounted trip bar extending transversely across at least two poles of the breaker and rotatable from a normal position to a tripping position to eifect release of said actuating member,

the weight distribution of said bar being such that the forces acting on said bar are substantially balanced at each and every point of its length so as to prevent thebar from being subjected to torsional stress and to prevent its being moved in response to jarring forces.

18. In a multi-pole circuit breaker having a plurality of pairs of separable contacts and an actuating member releasable to effect simultaneous opening of said pairs of contacts, the combination of a trip device comprising a pivoted trip bar extending across two or more poles of said breaker and movable from a normal position to a tripping position to effect release of said actuating member, said bar having spaced openings extending transversely therethrough, a plurality of pivot studs carried by the bar, one for each opening, said studs projecting into said openings and being disposed in alignment with their axis coinciding with the longitudinal axis of said bar, stationary bearing means extending into said openings and engaging said studs for pivotally mounting the bar and a removable spacer means disposed in at least one of said openings between the pivot stud and the opposite transverse wall of the opening for maintaining said bar in mounted position on said bearing means and for preventing longitudinal movement of said trip bar.

JEROME SANDIN. 

